Friction draft gear



Dec. l2, 1933. H, A HERNDON 1,939,303

FRICTION DRAFT GEAR Filed Sept. 28, 1928 2 Sheets-Sheet l n f Z J4 j? U'/4 /7 1.9 d l/0 j* 3 i ff /Z/f INVENTOR www, awww( Patented Dec.'2,13933;

UNITED STATES FRICTION DRAFT GEAR Henry A.-Herndon, Chicago, Ill.,assignor to The Bradford Patents Corporation, New York, N. Y., acorporation of Delaware Application September 28, 1928 Serial No.309,005

1o claims. (o1. 21a-*33) My invention relates to friction draft gearsand has for its general object the provision of an efficient draft gearcapable of developing a high resistance during closure and insuring thereturn of the members to release position when the closing force isrelieved.

The invention has other objects and advantages as will appear inconnection with the accompanying drawings in which Fig. 1 is a plan viewof the preferred form of draft gear,` partly in section; Fig. 2 is aVertical section through the axis of the gear; Fig. 3 is a sectionalplan showing the gear under compression; Figs. 4 and 5 are sectionalviews taken respectively on lines 4-4 and 5 5 of Fig. 2; and Figs. 6,'7, 8, 9, 10, 1l, 12, 13 and 14 are perspective views of component partsof the gear. 'I'he draft sills 1 may be of usual construction. Theycarry front draft lugs 2, and rear draft lugs 3. The draft gear,inclusive of the follower 4 thereof, is located between the inner andouter pairs of draft lugs and is enclosed by the yoke 5. This yoke andthe members enclosed thereby are supported by the draft gear carrier 6.The coupler 7 hasits inner end in contact with the draft gear followerand is attached to the yoke by the draft key 8, whichi passes throughthe sills.

The draft gear includes Va spring housingv 9, which preferably enclosesan outer coil spring 10, constitutingan applicationspring, and an innercoil spring l1, constituting a release spring. At the open end' of thespring housing is a friction housing 12, attached to-th'e spring housingbyv rivets 13 or other suitable fastening means. Members 9 and 12together constitute a load sustaining column member and may be madeintegral although the construction illustrated is preferable. The:friction housing 12 has the interior surfaces of the two oppositevertical sides in l the form of arcuate sections of cylinders, the axes40 preferably converging towardthe inner end of the housing. Thelothertwo sides are preferablyv straight and are provided with lugs l12.Fricdrical form adapted to contact with the cylindrical surfaces of `thefriction housing. VVEachopposite side of each friction shoe is providedwith a y of' each of the wedge blocks is a plane surface from the draftgear follower.

parallel to the axis of the gear. The outer end of each wedge block isadapted to contact with the follower and the inner end is in Contactwith the inner coil spring 11.

Normally stationary friction plates 16 are in Vcontact with the planesurfaces of the wedge blocks and have capacity for relative movement inthe friction housing limited by engagement of shoulders 12a on theplates with the lugs 12 and also by keys 17 which extend through theplates and through the upper and lower walls of the housing 12, theslots l'la in the plates being of greater width than the keys. Betweenthe `stationary friction plates is a central friction 'of assemblydispenses with projections on the wedge blocks to retain them inposition, the machining or grinding of the friction surfaces beingfacilitated.

In the operation of the draft gear, forces transmitted fromfthe couplerin bufling or pulling, set upv pressure between the` follower plate andthe wedge blocks 15. Part of this force is transmitted to the inner coilspring 11, and part is transferred through the wedging surfaces to thefriction shoes 14; The inward movement of these shoes is resisted by theouter coil spring 10. The resistance of the outer coil spring sets up awedging force which produces pressure on the frictionsurfaces as theparts move inward and this' is augmented by the relative movementbetween the'wedge blocks and friction shoes caused by the taper of thefriction housing. At'the beginning of the movement of the friction shoestion shoes 14 are disposed withinjthe friction housing. Each shoe hasits outer side of cylinandA wedge blocks, the stationary friction plates146 and the `central friction block move inward without shiftingrelatively to the wedge blocks until the shoulders` 12a onl thestationary friction plates 16 come in contact with the lugs 12' on thefriction housing. As soon as contact is established between thestationary friction plates and the lugs 12', the inward movement of thestationary frictionplate and the central friction block is arrested andthe resistance of the gear becomes increased by the development offrictional resistance between the Vwedge blocks and the stationaryfriction plates. After the draft gear follower has moved inward adistance equal to the clearance in released position between thestationary friction plates and the lugs 12', plus the clearance betweenthe follower 'and the central friction block 18, such follower comes incontact with the central friction block which thereafter moves inward asactuated bythe follower. As soon as the central friction block commencesto move relatively to the stationary friction plates, the frictionalresistance of the draft gear is further augmented. ,l Y

From thisdescription of the operation of vthe draft gear, it will benoted that` at the initial movement frictional resistance is set up onlybetween the friction shoes and the friction housing, this resistancebeing increased in stagesras the friction surfaces of the wedge blocksand of the central friction block come into action.

When the force tending to compress the draft gear is relieved, the forceof the outer and inner coil springs acts to return the friction membersto released position. At the beginning of the release movement thefriction shoes 14, wedge blocks l5, stationary friction plates 16, andcentral friction block 18, move outward as a unit without relativemovement between any of the parts until the clearance between the keys17 and the openings in the stationary friction plates is taken up. Whenthe outward movement of vthe stationary friction plates is arrested, theforce exerted by the inner coil spring serves to move the wedge blocksoutward, overcoming the friction between the Wedge blocks and stationaryfriction plates. A short additional outward movement of the wedge blocksand friction shoes .brings the outer coil vspring in contact with thecentral friction block. Thereupon,l part Vofthe force exerted by theouter coil .spring is absorbed inv overcoming the frictional resistanceof the central friction blocks. Consequently, the force exerted bytheouter coil spring against the friction shoes which tends to setuppressure on the surfaces of the friction members is decreased andrelease of the parts is facilitated.

Changes may be made without departing from the invention.

Having thus described my invention, I claim:

1. A friction draft gear including a frictionV housing; a group offriction members within said housing inclusive of friction shoes and apair of wedge blocks in wedging relation with said' shoes and furtherinclusive of a'friction means interposed between said members; a keepercooperating with the friction means and connecting one pair of frictionmembers; means for keying certain of the friction members to thehousing, a spring opposingv the inward movement of said members; and aspring pressing on the wedge blocks and tending to force them to releaseposition. v

2. A friction draft Ygear including a friction housing; a group offriction' members within said'housing inclusive of friction shoes and apair of wedge blocks in wedging relation with said shoes; a frictionproducing means interposed between said members and including outer andinner plates; a lug on the housing limiting the movement of the frictionproducing means in one direction and a key limiting the movement of theouter friction plates in the opposite direction; a spring opposinginward movement of said shoes; and a spring pressing on the wedgeVblocks to force them torelease position.

Y 3. In a friction draft gear, a housing, a pair of shoes in frictionaland wedging engagement therewith, a pair of wedge members cooperatingwith said shoes, and an additional friction producing means locatedbetween said wedge members and including relatively movable outer andinner plates of which the outermost are in fricional engagement with thewedge members and of which the innermost is slidableV in frictionalengagement with the outermost, said outermost plates being formed withslots, and keys passing through said slots and anchored to the housing.

4. AIn a friction draft gear, a housing, a pair of shoes in frictionaland wedging engagement therewith, a pair of wedge members cooperatingwith said shoes, and a sequentially energized additional frictionproducing means located between said wedge members and includingrelatively movable plates of which the outermost are substantially fixedwith respect to the housing and in frictional engagement with the wedgemembers and of which the innermost is slidable `in frictional engagementwith the outermost, and

to the bottom and top of the housing and passing no through said slots.v

6. In a friction draft gear, a housing constitut- -ing a load sustainingcolumn member, apair of shoes having wedging engagement therewith, wedgeblocks located inwardly of and cooperating with said shoes, and anadditional resistance means located between and cooperating withV therwedge blocks and including a pair of outer plates and an interposedplate, said `interposed plate being slidable, said outerplates beingformed with vertically extending slots, and keys anchored to the bottomand top ofthe housing and passing through said slots, said keys being ofless width than the slots to enable said outer plates to move to alimited extent in aflongitudinal direction.

'7, In a frictionldraft gear, a housing constituting ak load sustainingcolumn member, a pair of shoes having wedging engagement therewith,wedge blocks located inwardly of andcooperating rkwith said shoes, andan additional resistancemeans located between and cooperating with thei' wedge blocks and including a pair of outer plates and an interposedplate, said interposed plate being slidable, said outer plates beingformed with vertically extending slots, keys anchored4 to the bottom andtop of the housing and passing through said slots, and'lugs'ion theinside of the housing engageable byjsaid outer plates and serving asabutment means to take the end thrust thereof and relieve the strain onsaid keys.

8; In a friction draft gear, a housing constituting a load sustainingcolumn'member, a pair of `,shoes having wedging engagement therewith,

wedge blocks located inwardly of and cooperating with said shoes, and anadditional resistance means located between and cooperating with thewedge blocks and including a pair of outer plates and an interposedplate movable relatively to one Aanother and with respect to the wedgeblocks,

and means cooperating with said outer plates for *i said outer platesand interposed plate being mov-l able inwardly as an assembly with thewedge blocks for a portion of the travel of the gear,

and means cooperating with said outer plates and the housing forlimiting the inward movement of the former whereby the wedge blocks maymove relatively thereto for the remainder of the travel of the gear.

10. In a friction draft gear, a housing constituting a load sustainingcolumn member, a pair of shoes having wedging engagement therewith,wedge blocks located inwardly of and cooperating with said shoes, and anadditional re-l sistance means located between and cooperating with thewedge blocks and including a pair of outer plates and an interposedplate movable relatively to one another and with respect to the wedgeblocks, and means carried by the housing and cooperating with said pairof outer plates and enabling them to move with the wedge blocks for aportion of the travel of the gear and then for holding the platesstationary while the wedge' blocks move with respect thereto during theremainder of the travel of the gear.

HENRY A. HERNDON.

